ghsa-wgxr-cxxg-w4cj
Vulnerability from github
Published
2025-07-04 15:31
Modified
2025-07-04 15:31
Details

In the Linux kernel, the following vulnerability has been resolved:

atm: atmtcp: Free invalid length skb in atmtcp_c_send().

syzbot reported the splat below. [0]

vcc_sendmsg() copies data passed from userspace to skb and passes it to vcc->dev->ops->send().

atmtcp_c_send() accesses skb->data as struct atmtcp_hdr after checking if skb->len is 0, but it's not enough.

Also, when skb->len == 0, skb and sk (vcc) were leaked because dev_kfree_skb() is not called and sk_wmem_alloc adjustment is missing to revert atm_account_tx() in vcc_sendmsg(), which is expected to be done in atm_pop_raw().

Let's properly free skb with an invalid length in atmtcp_c_send().

[0]: BUG: KMSAN: uninit-value in atmtcp_c_send+0x255/0xed0 drivers/atm/atmtcp.c:294 atmtcp_c_send+0x255/0xed0 drivers/atm/atmtcp.c:294 vcc_sendmsg+0xd7c/0xff0 net/atm/common.c:644 sock_sendmsg_nosec net/socket.c:712 [inline] __sock_sendmsg+0x330/0x3d0 net/socket.c:727 _syssendmsg+0x7e0/0xd80 net/socket.c:2566 _sys_sendmsg+0x271/0x3b0 net/socket.c:2620 __sys_sendmsg net/socket.c:2652 [inline] __do_sys_sendmsg net/socket.c:2657 [inline] __se_sys_sendmsg net/socket.c:2655 [inline] __x64_sys_sendmsg+0x211/0x3e0 net/socket.c:2655 x64_sys_call+0x32fb/0x3db0 arch/x86/include/generated/asm/syscalls_64.h:47 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xd9/0x210 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was created at: slab_post_alloc_hook mm/slub.c:4154 [inline] slab_alloc_node mm/slub.c:4197 [inline] kmem_cache_alloc_node_noprof+0x818/0xf00 mm/slub.c:4249 kmalloc_reserve+0x13c/0x4b0 net/core/skbuff.c:579 __alloc_skb+0x347/0x7d0 net/core/skbuff.c:670 alloc_skb include/linux/skbuff.h:1336 [inline] vcc_sendmsg+0xb40/0xff0 net/atm/common.c:628 sock_sendmsg_nosec net/socket.c:712 [inline] __sock_sendmsg+0x330/0x3d0 net/socket.c:727 _syssendmsg+0x7e0/0xd80 net/socket.c:2566 _sys_sendmsg+0x271/0x3b0 net/socket.c:2620 __sys_sendmsg net/socket.c:2652 [inline] __do_sys_sendmsg net/socket.c:2657 [inline] __se_sys_sendmsg net/socket.c:2655 [inline] __x64_sys_sendmsg+0x211/0x3e0 net/socket.c:2655 x64_sys_call+0x32fb/0x3db0 arch/x86/include/generated/asm/syscalls_64.h:47 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xd9/0x210 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f

CPU: 1 UID: 0 PID: 5798 Comm: syz-executor192 Not tainted 6.16.0-rc1-syzkaller-00010-g2c4a1f3fe03e #0 PREEMPT(undef) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025

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{
  "affected": [],
  "aliases": [
    "CVE-2025-38185"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-07-04T14:15:25Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\natm: atmtcp: Free invalid length skb in atmtcp_c_send().\n\nsyzbot reported the splat below. [0]\n\nvcc_sendmsg() copies data passed from userspace to skb and passes\nit to vcc-\u003edev-\u003eops-\u003esend().\n\natmtcp_c_send() accesses skb-\u003edata as struct atmtcp_hdr after\nchecking if skb-\u003elen is 0, but it\u0027s not enough.\n\nAlso, when skb-\u003elen == 0, skb and sk (vcc) were leaked because\ndev_kfree_skb() is not called and sk_wmem_alloc adjustment is missing\nto revert atm_account_tx() in vcc_sendmsg(), which is expected\nto be done in atm_pop_raw().\n\nLet\u0027s properly free skb with an invalid length in atmtcp_c_send().\n\n[0]:\nBUG: KMSAN: uninit-value in atmtcp_c_send+0x255/0xed0 drivers/atm/atmtcp.c:294\n atmtcp_c_send+0x255/0xed0 drivers/atm/atmtcp.c:294\n vcc_sendmsg+0xd7c/0xff0 net/atm/common.c:644\n sock_sendmsg_nosec net/socket.c:712 [inline]\n __sock_sendmsg+0x330/0x3d0 net/socket.c:727\n ____sys_sendmsg+0x7e0/0xd80 net/socket.c:2566\n ___sys_sendmsg+0x271/0x3b0 net/socket.c:2620\n __sys_sendmsg net/socket.c:2652 [inline]\n __do_sys_sendmsg net/socket.c:2657 [inline]\n __se_sys_sendmsg net/socket.c:2655 [inline]\n __x64_sys_sendmsg+0x211/0x3e0 net/socket.c:2655\n x64_sys_call+0x32fb/0x3db0 arch/x86/include/generated/asm/syscalls_64.h:47\n do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]\n do_syscall_64+0xd9/0x210 arch/x86/entry/syscall_64.c:94\n entry_SYSCALL_64_after_hwframe+0x77/0x7f\n\nUninit was created at:\n slab_post_alloc_hook mm/slub.c:4154 [inline]\n slab_alloc_node mm/slub.c:4197 [inline]\n kmem_cache_alloc_node_noprof+0x818/0xf00 mm/slub.c:4249\n kmalloc_reserve+0x13c/0x4b0 net/core/skbuff.c:579\n __alloc_skb+0x347/0x7d0 net/core/skbuff.c:670\n alloc_skb include/linux/skbuff.h:1336 [inline]\n vcc_sendmsg+0xb40/0xff0 net/atm/common.c:628\n sock_sendmsg_nosec net/socket.c:712 [inline]\n __sock_sendmsg+0x330/0x3d0 net/socket.c:727\n ____sys_sendmsg+0x7e0/0xd80 net/socket.c:2566\n ___sys_sendmsg+0x271/0x3b0 net/socket.c:2620\n __sys_sendmsg net/socket.c:2652 [inline]\n __do_sys_sendmsg net/socket.c:2657 [inline]\n __se_sys_sendmsg net/socket.c:2655 [inline]\n __x64_sys_sendmsg+0x211/0x3e0 net/socket.c:2655\n x64_sys_call+0x32fb/0x3db0 arch/x86/include/generated/asm/syscalls_64.h:47\n do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]\n do_syscall_64+0xd9/0x210 arch/x86/entry/syscall_64.c:94\n entry_SYSCALL_64_after_hwframe+0x77/0x7f\n\nCPU: 1 UID: 0 PID: 5798 Comm: syz-executor192 Not tainted 6.16.0-rc1-syzkaller-00010-g2c4a1f3fe03e #0 PREEMPT(undef)\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025",
  "id": "GHSA-wgxr-cxxg-w4cj",
  "modified": "2025-07-04T15:31:08Z",
  "published": "2025-07-04T15:31:08Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-38185"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1b0ad18704913c92a3ad53748fbc0f219a75b876"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2f370ae1fb6317985f3497b1bb80d457508ca2f7"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3261c017a7c5d2815c6a388c5a3280d1fba0e8db"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a4b0fd8c25a7583f8564af6cc910418fb8954e89"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c19c0943424b412a84fdf178e6c71fe5480e4f0f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c9260c837de1d2b454960a4a2e44a81272fbcd22"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ca00f0e6d733ecd9150716d1fd0138d26e674706"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e996507f59610e5752b8702537f13f551e7a2c96"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}


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